Electric alarm for pressure gages



G. D. EARLL. Electric Alarm for Pressure-Gages.

Patented April 6,1880.

N PETERS, PHOTO LITHUGRAPHER, WASHINGTON, D c.

UNITED STATES GEORGE D. EARLL, OF NEW YORK, N. Y.

ELECTRIC ALARM F OR PRESSURE-GAGES.

SPECIFICATION forming part of Letters Patent No. 226,165, dated April 6,1880.

Application filed November 28, 1879.

To all whom it may concern:

Be it known that I, GEORGE D. EARLL, of the city and county and State ofNew York, have invented a new and Improved Electric Alarm or Device forUse upon Steam-Pressure Gages, of which the followingis a description,reference being had to the accompanying drawings, and to the letters ofreference thereon, making a part of this specification.

Electric alarms have been heretofore used in connection with steampressure gages, but they have been so made as to be a part of the gageitself, and have required a particular or special construction of somepart of the gage, or they have been so constructed as to interfere moreor less with the continuous and free action of the gage as apressureindicator.

My improved alarm device can be attached to any steam or pressure gagein use, and without requiring any alteration in its parts, and does not,in any degree; interfere with the freest action of the gage as apressure-indicator under any and all pressures. It is also simple inarrangement, cheap in construction, and certain and automatic inoperation.

Figure 1 shows a pressure-gage with my electric-alarm device attached.Fig. 2 is a detached view of the circuitclosing device which is attachedto the gage. Fig. 3 is asectional view of Fig. 2 through the line a m.Fig. 4 is a detached view of one end of the index-hand by which thecircuit is closed.

A represents the dial of an ordinary pressure-gage, placed within a caseor shell, B, and upon which moves the index-hand C. To the shell or caseor dial of the gage, and connected therewith by screws 1 1, I attach thepart D, Fig. 2, which consists of a metal plate or rim, to, to which isfixed an insulated block or plate, Z), most conveniently and cheaplymade of hard rubber, which extends over the outer edge of the dial, andto the inner side or edge of which is connected a metal face-plate, 0,which is so connected therewith, as seen in Fi 3, that it will not be incontact with any part of the gage.

Connectin g with the metal plate a, as shown in Fig. 2, or directly withthe shell or case of the gage, is an insulated wire, 2, and anothersimilar wire, 2, passes into and through the insulated block or plateI), and connects with its metallic face-plate c. The other ends of suchwires connect with a suitable battery and alarm.

The plate 0 being insulated from the gage, the electric circuit betweenthe gage and bat tery and the alarm is open under ordinarycircumstances, and at such time or in such case no alarm is given; butwhenever contact or electrical connection is made between the gage andthe plate 0 the circuit will be closed and an alarm made. This contactis effected by means of or through the common index-hand O, whichindicates the pressure existing at any time when the pressure issufficient to bring the arm or end 3 of the index-hand upon the plate 0,the part D being placed on the gage in such location that the end 3 ofthe index-hand will not come in contact with the plate 0 until thepressure has become such that danger may be apprehended or specialnotice is desired.

Fig. 1 shows the index-hand in two positions, the heavy linesrepresenting it in a position when the circuit is open and no alarmproduced, and the dottedlines showing it when in contact with plate 0,at which time the circuit is closed and the alarm made or attentioncalled.

To insure a continued, free, and proper action of the gage as apressure-indicator, it is necessary that the contact betweentheindexhand and the plate 0 should be effected or the circuit closed insuch a manner as not to interfere in any manner with the free andcontinuous movement of the index-hand and the natu *al action andoperation of the gage. This I accomplish by so constructing andarranging the parts that theindex-hand will not strike or press againstthe metal plate 0, and thus in any degree obstruct the free movement ofthe hand or affect the natural action of the gage, but will slide uponor pass over such parts, and with the least possible friction orresistance.

To produce the least friction between the hand 3 and the plate cas theformer slides upon or passes over the latter, I place upon the end ofthe hand a loosely-revolving wheel, 3, the hand 0 being also sosupported 011 its standard that the periphery of the friction-wheel 3will be only a very little below the horizontal plane of the plate 0.

With such a construction and arrangement of the parts by which thecircuit is closed the gage will act as free] y and perfectly as a presslire-indicator asif the alarm werenotconnected with it, and Wlllcontinue so to act after the alarm has been given, and the hand canfreely pass beyond the platec if pressure is increased.

The arrangement of the plate 0, as before de scribed, also renders itpossible to secure acon tinuous alarm during any desired length of timeor during any desired number of degrees.

My improved electric-alarm device, as will be evident from the foregoingdescription, can be attached to and combined with any pressure-gagewithout any change in its construction, and will not in any mannerinterfere with its ready action as a pressure-indicator, and is simplein construction and automatic in operation.

What is claimed as new is The circuit-closing device D, consisting,substantially, of rim a, insulated block b, and plate 0, in combinationwith the indcxhaud and dial of a pressure-gage, the index-hand anddevice D being connected by properly-insulated wires with a suitablebattery and alarm, for the purposes set forth.

GEORGE D. EARLL.

Witnesses:

S. NuLsoN WHITE, SAMUEL LEA.

